Attention-deficit/hyperactivity disorder (ADHD) is well known to be a highly impairing and strongly persistent condition in boys and men, but knowledge about its long-term consequences in girls and women is severely limited. The core objective is to redress the major dearth of longitudinal data on females with ADHD via a rigorous, prospective, 15-year follow-up investigation, into the age span of the mid-20s, of a well-characterized, ethnically- and socioeconomically-diverse sample of girls with carefully diagnosed ADHD (n = 140), plus an age- and ethnicity/race-matched sample of comparison girls (n = 88). To the investigator's knowledge, this sample comprises the largest in existence of girls with this disorder, ascertained prior to adolescence. During earlier iterations of the curren grant, participants were recruited and investigated between the ages of 6 and 12 years (Wave 1) and followed systematically in early to mid- adolescence (Wave 2, ages 11-18 years; 92% retention) and most recently in a 10-year follow-up in late adolescence/early adulthood (Wave 3, ages 17-24 years; 95% retention). Key aims for projected Wave 4 assessments, during the age span of 22-29 years, are to characterize outcomes of these women across multiple domains of functioning, including ADHD symptoms and subtypes, externalizing and internalizing behavior patterns (including antisocial behavior, mood disturbance, eating pathology, self-injurious and suicidal behavior), substance use/abuse, academic and vocational performance, neuropsychological skills, peer and family relations, health-related parameters, and service utilization. The overall goal is to understand trajectories of development, impairment, and (in some cases) positive adjustment, with the strongest focus on outcomes of major clinical and conceptual importance to female development: (a) educational attainment and employment status; (b) relationships/interpersonal functioning; (c) self-harm (i.e., suicidal behavior and sel-injury, which were present at strikingly high rates during the 10-year follow- up); (d) executive functioning; and (e) health-related behaviors. The project's established methods of ascertaining positive adjustment will be followed. A related aim is to characterize baseline predictors and moderators and adolescent mediators of adult functioning, via stringent and sophisticated statistical methods. The proposed Wave 4 assessments feature psychometrically rigorous, multi-method, and multi- informant measures, many of which are identical or parallel across all four waves, facilitating growth-curve and growth-mixture modeling. Because of (i) major gaps in knowledge surrounding adult adjustment of women with ADHD and (ii) the potential for unique findings to emerge during the age span of the mid-20s, examination of female developmental trajectories into adulthood is a key priority. Such aims will be met in this innovative and rigorou investigation, with the potential to enhance both basic and clinical science.